code: def test_1_stacked_ensemble(self):
      from lightwood.ensemble.stacked_ensemble import StackedEnsemble
  
      df = pd.read_csv("tests/data/concrete_strength.csv")[:500]
      target = "concrete_strength"
  
      pdef = ProblemDefinition.from_dict(
          {"target": target, "time_aim": 80}
      )
      jai = json_ai_from_problem(df, pdef)
      jai.model["module"] = "StackedEnsemble"
  
      predictor = predictor_from_json_ai(jai)
      predictor.learn(df)
      predictor.predict(df)
      self.assertTrue(isinstance(predictor.ensemble, StackedEnsemble))
  
file_path: lightwood/tests/integration/basic/test_regression.py
imports: from type_infer.dtype import dtype
  import unittest
  import pandas
  from sklearn.metrics import r2_score
  from lightwood.api.types import ProblemDefinition
  from lightwood.api.high_level import json_ai_from_problem, predictor_from_json_ai
  from lightwood import __version__
label_desc: Use image node_id 2 for calling the TestBasic obj's underlying member method code with example usage: obj.test_1_stacked_ensemble() without return types